The present invention relates to an x-ray optic. More specifically the present invention relates to an improved Kirkpatrick-Baez optical apparatus to condition, direct, focus, or collimate an x-ray beam.
There are various applications which utilize conditioned, directed, collimated, or focused x-rays. For example, medical radiotherapy systems utilize x-rays to destroy malignant tissue, x-ray diffraction or microdiffraction analysis systems channel x-ray radiation at a sample crystal to generate a diffraction pattern corresponding to its lattice structure, and x-ray fluorescence and spectroscopy systems employ directed x-ray beams.
In many applications it is desirable to direct a beam in two dimensions. To collimate a beam in two dimensions, the traditional Kirkpatrick-Baez optical scheme may be employed. Two crossed mirrors arranged in sequential order collimate a divergent x-ray beam along two directions independently. With a point source, this sequential order system equipped with two parabolic mirrors will provide a parallel beam. With a finite source this system will provide a beam with different divergences in two directions. This sequential order system equipped with two elliptical mirrors can give a perfect real point image with a point source at its focal point. For a field object, the image will be magnified or demagnified by the system. Since the two mirrors are different distances from the object, the magnification will be different for both directions.
The present invention employs an innovative variation of the Kirkpatrick-Baez system employing a side-by-side scheme and multi-layer Bragg x-ray reflecting surfaces. The side-by-side system provides a solution to the problems associated with a sequential system as well as providing other advantages. The mirrors in a side-by-side system can be arranged at the most appropriate location for optimized optical performance to increase flux, shortening the time needed for data collection by an x-ray detection device. The side-by-side system will suffer less from surface imperfections and is prealigned and bonded to prevent alignment errors. The side-by-side optic is also much more compact than that of a sequential scheme enabling it to be used in applications where space is at a premium. The performance of a side by side optic can be even further improved by incorporating graded-d multi-layer Bragg x-ray reflectors. The multi-layer reflectors have a large reflection angle resulting in higher collection efficiency and provide the ability to select the frequencies of reflected x-rays.